1. Field of the Invention
The present invention relates to an improved suspension system for a motor vehicle, and more particularly to a motor vehicle suspension system having strain detector means for detecting a strain of the suspension which represents the degree to which the suspension is deteriorated, i.e., a deteriorated condition of the suspension.
2. Description of the Relevant Art
Japanese Laid-Open Utility Model Publication No. 60(1985)-106807 discloses a strut-type suspension which comprises a shock absorber with a coil spring. The shock absorber is coupled at its upper end to a motor vehicle body through a resilient member and also coupled at its lower end to a steering knuckle. An electrically conductive rubber layer serving as a strain detector is disposed on the resilient member. A running condition of the motor vehicle can be confirmed if a change in the electric resistance of the rubber layer, as it is elastically expanded and contracted, is detected.
Another suspension system disclosed in Japanese Laid-Open Patent Publication No. 1(1989)-266005 includes a leaf spring with its opposite ends angularly movably coupled to respective left and right steering knuckles. The leaf spring is associated with a strain gauge which detects any strain of the leaf spring when the leaf spring flexes, so that a change in the load on the road wheels or a change in the height of the motor vehicle can be known from the detected signal from the strain gauge.
The above conventional suspension systems are not designed to detect a deteriorated condition of the suspension, although the strain detector or gauge is able to give information with respect to the running condition of the motor vehicle. However, it is desirable to be able to detect a deteriorated condition of motor vehicle suspensions from the standpoint of maintaining the quality of the suspensions above a certain level.